bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
#require no-chg
Test basic extension support
$ cat > foobar.py <<EOF
> import os
> from mercurial import commands, registrar
> cmdtable = {}
> command = registrar.command(cmdtable)
> configtable = {}
> configitem = registrar.configitem(configtable)
> configitem(b'tests', b'foo', default=b"Foo")
> def uisetup(ui):
> ui.debug(b"uisetup called [debug]\\n")
> ui.write(b"uisetup called\\n")
> ui.status(b"uisetup called [status]\\n")
> ui.flush()
> def reposetup(ui, repo):
> ui.write(b"reposetup called for %s\\n" % os.path.basename(repo.root))
> ui.write(b"ui %s= repo.ui\\n" % (ui == repo.ui and b"=" or b"!"))
> ui.flush()
> @command(b'foo', [], b'hg foo')
> def foo(ui, *args, **kwargs):
> foo = ui.config(b'tests', b'foo')
> ui.write(foo)
> ui.write(b"\\n")
> @command(b'bar', [], b'hg bar', norepo=True)
> def bar(ui, *args, **kwargs):
> ui.write(b"Bar\\n")
> EOF
$ abspath=`pwd`/foobar.py
$ mkdir barfoo
$ cp foobar.py barfoo/__init__.py
$ barfoopath=`pwd`/barfoo
$ hg init a
$ cd a
$ echo foo > file
$ hg add file
$ hg commit -m 'add file'
$ echo '[extensions]' >> $HGRCPATH
$ echo "foobar = $abspath" >> $HGRCPATH
$ filterlog () {
> sed -e 's!^[0-9/]* [0-9:]* ([0-9]*)>!YYYY/MM/DD HH:MM:SS (PID)>!'
> }
Test extension setup timings
$ hg foo --traceback --config devel.debug.extensions=yes --debug 2>&1 | filterlog
YYYY/MM/DD HH:MM:SS (PID)> loading extensions
YYYY/MM/DD HH:MM:SS (PID)> - processing 1 entries
YYYY/MM/DD HH:MM:SS (PID)> - loading extension: foobar
YYYY/MM/DD HH:MM:SS (PID)> > foobar extension loaded in * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - validating extension tables: foobar
YYYY/MM/DD HH:MM:SS (PID)> - invoking registered callbacks: foobar
YYYY/MM/DD HH:MM:SS (PID)> > callbacks completed in * (glob)
YYYY/MM/DD HH:MM:SS (PID)> > loaded 1 extensions, total time * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - loading configtable attributes
YYYY/MM/DD HH:MM:SS (PID)> - executing uisetup hooks
YYYY/MM/DD HH:MM:SS (PID)> - running uisetup for foobar
uisetup called [debug]
uisetup called
uisetup called [status]
YYYY/MM/DD HH:MM:SS (PID)> > uisetup for foobar took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> > all uisetup took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - executing extsetup hooks
YYYY/MM/DD HH:MM:SS (PID)> - running extsetup for foobar
YYYY/MM/DD HH:MM:SS (PID)> > extsetup for foobar took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> > all extsetup took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - executing remaining aftercallbacks
YYYY/MM/DD HH:MM:SS (PID)> > remaining aftercallbacks completed in * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - loading extension registration objects
YYYY/MM/DD HH:MM:SS (PID)> > extension registration object loading took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> > extension foobar take a total of * to load (glob)
YYYY/MM/DD HH:MM:SS (PID)> extension loading complete
YYYY/MM/DD HH:MM:SS (PID)> loading additional extensions
YYYY/MM/DD HH:MM:SS (PID)> - processing 1 entries
YYYY/MM/DD HH:MM:SS (PID)> > loaded 0 extensions, total time * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - loading configtable attributes
YYYY/MM/DD HH:MM:SS (PID)> - executing uisetup hooks
YYYY/MM/DD HH:MM:SS (PID)> > all uisetup took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - executing extsetup hooks
YYYY/MM/DD HH:MM:SS (PID)> > all extsetup took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - executing remaining aftercallbacks
YYYY/MM/DD HH:MM:SS (PID)> > remaining aftercallbacks completed in * (glob)
YYYY/MM/DD HH:MM:SS (PID)> - loading extension registration objects
YYYY/MM/DD HH:MM:SS (PID)> > extension registration object loading took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> extension loading complete
YYYY/MM/DD HH:MM:SS (PID)> - executing reposetup hooks
YYYY/MM/DD HH:MM:SS (PID)> - running reposetup for foobar
reposetup called for a
ui == repo.ui
YYYY/MM/DD HH:MM:SS (PID)> > reposetup for foobar took * (glob)
YYYY/MM/DD HH:MM:SS (PID)> > all reposetup took * (glob)
Foo
$ cd ..
$ echo 'foobar = !' >> $HGRCPATH